Aluminum flatbed with unique front connection

ABSTRACT

A drop deck trailer frame includes a front section having a first upper surface, a rear section having a second upper surface lower than the first upper surface, and an improved connection between the front and rear sections which tends to reduce cracking which commonly occurs in drop deck trailer frames due to the stresses in the region of the connection. The connection preferably includes a semicircular weld. In addition, heat treated bent flanges are typically used to provide additional strength. Fasteners such as bolts are also typically used to connect various flanges.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/571,448, filed Aug. 10, 2012, which is a continuation of U.S. patentapplication Ser. No. 13/298,434, filed Nov. 17, 2011 (now U.S. Pat. No.8,256,799), which is a continuation of U.S. patent application Ser. No.12/902,432, filed Oct. 12, 2010 (now U.S. Pat. No. 8,096,583), which isa continuation of U.S. patent application Ser. No. 12/006,649, filedJan. 4, 2008 (now U.S. Pat. No. 7,832,767); the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to flatbed trailers. Moreparticularly, the present invention relates to a drop deck trailer.Specifically, the invention relates to the front connection between theupper and lower decks of the drop deck trailer.

2. Background Information

Drop deck trailers are well known in the art and include an upper deckat the front of the trailer and a lower deck which is connected to andextends rearwardly from the upper deck. This configuration allows forthe upper to be connected to an elevated hitch such as a fifth wheelwhile the lower deck may be position at a lower height to provide foradditional storage within the height perimeters required by variousregulations for roadways and highways.

One problem which is commonly seen in drop deck trailers is theformation of cracks or other deterioration within the structureconnecting the upper and lower decks of the trailer frame due to theinherent forces acting along this region of the frame especially whenthe trailer is fully loaded. The present invention addresses this andother problems in the art.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention may provide a drop deck trailerframe comprising: a front section having a first upper surface; a rearsection having a second upper surface lower than the first uppersurface; an S-shaped flange on the front section; an I-beam of the rearsection defining the second upper surface and comprising a verticalplate having a top and a bottom, an upper flange secured to the top ofthe vertical plate and having a front end, and a lower flange secured tothe bottom of the vertical plate and having a front end; a firstupwardly extending flange which extends from adjacent the front end ofthe upper flange to adjacent the front end of the lower flange; and asecond upwardly extending flange which extends from adjacent the frontend of the upper flange to adjacent the front end of the lower flange.

In another aspect, the invention may also provide a drop deck trailerframe comprising: a front section having a first upper surface; a rearsection having a second upper surface lower than the first uppersurface; an S-shaped flange on the front section; an I-beam of the rearsection defining the second upper surface and comprising a verticalplate having a top and a bottom, an upper flange secured to the top ofthe vertical plate and having a front end, and a lower flange secured tothe bottom of the vertical plate and having a front end; an upwardlyextending flange which extends from adjacent the front end of the upperflange to adjacent the front end of the lower flange; and an L-shapedflange adjacent the upwardly extending flange.

In another aspect, the invention may further provide a drop deck trailerframe comprising: a front section having a first upper surface; a rearsection having a second upper surface lower than the first uppersurface; a longitudinally extending I-beam of the rear section definingthe second upper surface and comprising a vertical plate having a topand a bottom, an upper flange secured to the top of the vertical plateand having a front end, and a lower flange secured to the bottom of thevertical plate and having a front end; a first upwardly extending flangeof the rear section which extends from adjacent the front end of theupper flange to adjacent the front end of the lower flange and which hasa lower end; a second upwardly extending flange of the front sectionwhich extends from adjacent the front end of the upper flange toadjacent the front end of the lower flange, which extends upwardlybeyond the upper flange and which has a lower end; a longitudinallyextending third flange of the front section which extends below thelower ends of the first and second upwardly extending flanges andincludes a generally horizontal tongue which extends rearwardly beyondthe lower ends of the first and second upwardly extending flanges andbelow the lower flange; a plurality of first bolts extending from thefirst upwardly extending flange to the second upwardly extending flange;and a plurality of second bolts extending from the tongue to the lowerflange of the I-beam.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a side elevational view of the drop deck trailer of thepresent invention hitched to a tractor via a fifth wheel.

FIG. 2 is a top plan view taken on line 2-2 of FIG. 1 shown the frontconnection region of the trailer with the upper and lower decks shown inphantom.

FIG. 3 is a side elevational view of the front connection.

FIG. 4 is an exploded perspective view of the front connection.

FIG. 5 is a perspective view of the front connection when assembled.

FIG. 6 is an end elevational view looking forward on the L-shapedstructure of the connection.

FIG. 7 is a sectional view taken on line 7-7 of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

The front connection of the present invention as shown generally at 10in FIGS. 3 and 5. FIG. 1 shows front connection 10 as part of a dropdeck trailer 12 which is hitched to a towing vehicle in the form of atractor 14 via a fifth wheel hitch 16. Trailer 12 includes front andrear sections 18 and 20 which respectively include upper and lower decks22 and 24. A vertical decking member 38 (FIGS. 1, 3) is connected to andextends between the rear end of upper deck 22 and the front end of lowerdeck 24 to define the boundary therebetween. Member 38 and decks 22 and24 may be formed of metal, wood or other suitable materials. As shown inFIG. 2, trailer 12 includes a frame comprising first and secondlongitudinally extending parallel rails 26 and 28 connected adjacent thefront ends by a cross member 30 which extends axially therebetween andserves as a hitch support on which a hitch member 32 is mounted forconnection to fifth wheel 16. Adjacent the rear ends of rails 26 and 28,a wheel mounting structure 34 is connected to and extends axiallybetween rails 26 and 28 to support wheels 36, as shown in FIG. 1. Rails26 and 28 are substantially identical or are mirror images of oneanother and thus each include a front connection 10. Each of rails 26and 28 is formed of metal and typically the primary components areformed of an aluminum alloy. The use of an aluminum alloy provides for arelatively low cost and light weight structure for supporting decks 22and 24 and loads carried thereon.

Referring to FIGS. 3-5, connection 10 is described in greater detail.Rail 26 includes an L-shaped structure comprising an L-shaped plate 40,an L-shaped flange 42 connected to plate 40 and an S-shaped flange 44connected to plate 40. Plate 40 is substantially flat and substantiallyvertically oriented along a vertical longitudinally extending plane.Plate 40 includes a generally horizontal first leg 46 which extendslaterally in the longitudinal direction and a generally vertical secondleg 48 which is connected to the rear end of first leg 46 and extendsdownwardly therefrom. Plate 40 has an L-shaped edge 50 including agenerally horizontal edge segment 52 which extends laterally in alongitudinal direction and faces upwardly. Edge 50 further includes aconvex arcuate edge segment 54 which is connected to the rear end ofsegment 52, faces upwardly and rearwardly, and curves downwardly to adownwardly extending generally vertical edge segment 56. OppositeL-shaped edge 50, plate 40 has an S-shaped edge 58 which includes adownwardly facing generally horizontal edge segment 60 which extendslaterally in the longitudinal direction. A concave arcuate edge segment62 curves downwardly from the rear of segment 60 and faces forward anddownward. A short vertical edge segment 64 extends downwardly fromarcuate segment 62 and serves as a brief transition to another arcuatesegment 66 which is convex and curves in the opposite direction fromsegment 62 and thus downwardly and rearwardly. Vertical segment 64 facesforward while arcuate segment 66 faces forward and downward. A generallyhorizontal edge segment 68 extends rearwardly from arcuate segment 66and faces downwardly. Segment 68 intersects edge segment 56 of L-shapededge 50 at the lower rear corner of plate 40 and is substantiallyperpendicular to segment 56.

With continued reference to FIGS. 3-5, an L-shaped T-bar 70 extendsalong and is connected to the mating L-shaped edge 50 of plate 40. Asbest shown in FIGS. 4 and 5, T-bar 70 includes an L-shaped web 72 whichserves as the upright of the T-shaped cross section and an L-shapedcrossbar 74 which serves as the top of the T-shaped cross section andextends outwardly from web 72 in opposite directions. Crossbar 74 servesas L-shaped flange 42 in the exemplary embodiment. Crossbar 74 includesa generally horizontal segment 76 and arcuate segment 78 curvingdownward therefrom and a generally vertical segment 80 extendingdownwardly from arcuate segment 78 so that segments 76, 78 and 80 extendin an analogous manner respectively to edge segments 52, 54 and 56 ofthe L-shaped edge 50. Thus, web 72 has an L-shaped edge 82 which mateswith L-shaped edge 50 of plate 40. Edge 82 thus includes a generallyhorizontal segment 84, a concave arcuate segment 86 and a verticalsegment 88 which respectively mate with edge segments 52, 54 and 56 ofL-shaped edge 50 of plate 40. Horizontal segment 84 faces downwardly,arcuate segment 86 faces downwardly and forward and vertical segment 88faces forward. L-shaped edge 82 is connected to L-shaped edge 50 via anL-shaped continuous weld 90 which thus has analogous horizontal, arcuateand vertical segments. Segment 76 has a substantially horizontal uppersurface which serves as the upper surface of front section 18 of theframe upon which upper deck 22 is seated and secured.

An S-shaped T-bar 92 extends along and has a mating configuration withS-shaped edge 58 and is connected to plate 40 along edge 58. T-bar 92has an S-shaped web 93 and an S-shaped crossbar 95 connected to andextending outwardly in opposite directions from web 93. Crossbar 95 thusforms an S-shaped flange 44 in the exemplary embodiment. T-bar 92includes a generally horizontal segment 94, an arcuate segment 96curving downwardly and rearwardly therefrom, a short vertical segment 98at the bottom of arcuate segment 96, an arcuate segment 100 curvingdownwardly and rearwardly from vertical segment 98 in the oppositedirection of segment 96, and a generally horizontal segment 102extending rearwardly from arcuate segment 100. Web 93 thus includes anS-shaped edge 104 including a generally horizontal longitudinallyextending edge segment 106, a convex arcuate edge segment 108 curvingdownwardly and rearwardly therefrom, a short vertical edge segment 110extending down from segment 108, a concave arcuate edge segment 112curving downwardly and rearwardly from segment 110, and a generallyhorizontal edge segment 114 extending rearwardly from arcuate segment112. Edge segment 106 faces upwardly, arcuate edge segment 108 facesupwardly and rearwardly, vertical edge segment 110 faces rearwardly,arcuate edge segment 112 faces upwardly and rearwardly, and horizontalsegment 114 faces upwardly. Thus, edge segments 106, 108, 110, 112 and114 respectively matingly fit with segments 60, 62, 64, 66, and 68 ofS-shaped edge 58 of plate 40. S-shaped edges 58 and 104 are welded toone another via a continuous S-shaped weld 115.

A flat and generally horizontal tongue 116 extends rearwardly from alower end 118 of vertical segment 80 of L-shaped T-bar 70 and is formedfrom a portion of crossbar 95 from which web 93 has been removed. Moreparticularly, web 93 has a rearmost terminal end 120 which abuts web 72of L-shaped T-bar 70 adjacent lower end 118 thereof. Web 93 has beenremoved rearwardly of terminal end 120 so that only crossbar 95continues to project rearwardly in the form of tongue 116. Lower end 118of segment 80 abuts the upper surface of segment 102 at the front oftongue 116, and thus L-shaped flange 42 at its lowest and rearmostportion intersects S-shaped flange 44 along horizontal segment 102 toform an inverted T-shaped intersection. A first row of longitudinallyspaced through holes 122 is formed in tongue 116 generally along oneside thereof. Likewise, a second row of longitudinally spaced throughholes 124 formed in tongue 116 along the opposite side thereof so thatthe row of holes 124 is axially spaced from the row of holes 122 andholes 124 are also longitudinally offset from holes 122. Holes 122 and124 extend from the top surface of tongue of 116 to the bottom surfacethereof. Another row of vertically spaced through holes 126 (FIGS. 4, 6)is formed in vertical segment 80 of crossbar 74 extending from the frontto the rear surface thereof and positioned on the one side of web 72 andplate 40. Likewise, another row of vertically spaced through holes 128(FIG. 6) is formed in vertical segment 80 of crossbar 74 on the otherside of web 72 and plate 40.

In the exemplary embodiment, each of T-bars 70 and 92 is formed in anextrusion process. The extruded T-bars are bent to form their respectivearcuate segments and L-shaped and S-shaped configurations typically atroom temperature. A portion of web 93 is cut off or otherwise removedfrom the corresponding section of crossbar 95 to form tongue 116 aspreviously noted. Once the extruded T-bars are in their appropriateL-shaped and S-shaped configurations, they are heat treated in order toprovide additional strength and eliminate internal stresses caused bythe bending process. The heat treated T-bars are subsequently welded tothe L-shaped and S-shaped edges 50 and 58 of plate 40 at welds 90 and115 to form the rigid L-shaped structure of front section 18.

Referring to FIG. 4, rail 26 further includes a rigid connection member130 used in forming front connection 10. Connection member 130 is formedfrom a T-bar and includes a semicircular flat plate or web 132 and astraight vertically extending crossbar 134 connected to and extendingperpendicularly outwardly in opposite axial directions from web 132. Web132 lies in a substantially vertical longitudinally extending planeparallel to L-shaped plate 40 and is typically coplanar therewith.Crossbar 134 has upper and lower generally horizontal ends 136 and 138,first and second vertically extending lateral edges 140 and 142 andvertically extending front and rear surfaces 144 and 146. A first row ofvertically spaced through holes 148 is formed in crossbar 134 on oneside of web 132 extending from front surface 144 to rear surface 146 andrespectively alignable with holes 126 in vertical segment 80. Likewise,a second row of holes 150 is formed in crossbar 134 on the other side ofweb 130 and respectively alignable with holes 128 (FIG. 6) in verticalsegment 80. Web 130 has a straight vertically extending base 152 (FIG.3) which is connected to rear surface 146 of crossbar 134 and extendsfrom upper end 136 to lower end of 138. Web 130 extends rearwardly frombase 152 and terminates at a semicircular edge 154 which curvesrearwardly and downwardly from upper end 136 to a rearmost point 156 andthen downwardly and forward to lower end 138.

With reference to FIGS. 3-5, rail 26 includes a generally horizontalbeam 158 in the form of an I-beam which is connected to the L-shapedstructure and connection member 130 and extends rearwardly therefrom.I-beam 58 includes a flat vertical plate or web 160, an upper flange 162connected to and extending outwardly in opposite directions from the topof web 160, and a lower flange 164 connected to the bottom of web 160and extending outwardly in opposite directions therefrom. Web 160 liesin a substantially vertical longitudinally extending plane parallel toplate 40 and web 132 and is typically coplanar therewith. Upper flange162 has a front end 166, an upper surface 168 and a lower surface 170from which web 160 extends downwardly. Upper surface 168 issubstantially horizontal and serves as the upper surface of rear section20 of the frame on which rear lower deck 24 is seated and secured. Lowerflange 164 has a front end 172, an upper surface 174 from which web 160extends upwardly, and a lower surface 176. A first row of through holes178 is formed in lower flange 164 adjacent front end 172 thereof andextends from upper surface 174 to lower surface 176 on one side of web160. A second row of longitudinally spaced holes 180 is likewise formedin lower flange 164 on the other side of web 160. Holes 178 arerespectively alignable with holes 122 while holes 180 are respectivelyalignable with holes 124.

In the exemplary embodiment, I-beam 158 includes an inverted T-barincluding lower flange 164 and a lower half 182 of web 160. I-beam 158further includes another T-bar which includes upper flange 162 and anupper half 184 of web 160. Lower and upper halves 182 and 184 areconnected to one another along a substantially horizontal longitudinallyelongated weld 186. A front semicircular opening 188 is formed at thefront of web 160 and extends rearwardly therefrom and is bounded by asemicircular concavely curving front edge 190 having a lower front end192 spaced a short distance rearwardly from front end 172 of crossbar164 and an upper front end 194 (FIG. 3) which is likewise spacedrearwardly a short distance from front end 166 of upper flange 162. Weld186 intersects front edge 190 at its midpoint so that a quarter circleof edge 190 is form in lower half 182 and a quarter circle is formed inupper half 184. In the exemplary embodiment, web 160 has a height D1(FIG. 3) defined between lower surface 170 of upper flange 162 and uppersurface 174 of lower flange 164. Weld 186 is at the midway point betweensurfaces 170 and 174 so that lower half 182 and upper half 184 of plate160 each have a height D2 which is one half of height D1. In theexemplary embodiment, point 156 of web 132 and rear surface of 152 ofcrossbar 134 define therebetween a normal distance D3 which is equal todistance D1. Thus, connection member 130 may be formed of a T-bar havingthe same cross sectional configuration as that of the T-bars which areused to form I-beam 158.

When the various components are assembled as shown in FIGS. 3 and 5, web132 of connection member 130 is received within semicircular opening 188and crossbar 134 is received between upper and lower crossbars 162 and164 adjacent their respective front ends 166 and 172 and respectivelyforward of front ends 194 and 192 of edge 190. Thus, upper and lowerends 136 and 138 of crossbar 134 define a distance which is nearly thesame as distance D1 although typically slightly less so that crossbar134 can easily be received in between and welded to flanges 162 and 164.The convexly curving semicircular edge 154 of web 132 is of a matingconfiguration with concave semicircular edge 190 of web 160. Edge 154and edge 190 lie along a circular path having substantially the samediameter although the diameter along which edge 154 lies may be slightlyless to easily accommodate web 132 within opening 188. Once connectionmember 130 is positioned within space 188, edge 154 is welded to edge190 along a semicircular weld 196 while upper and lower ends 136 and 138of crossbar 132 are welded respectively to lower surface 170 of uppercrossbar 162 and upper surface 174 of crossbar 164. Fasteners in theform of bolts 198 and nuts 200 are typically used to form part of frontconnection 10. More particularly, bolts 198 are received through alignedholes 126 and 148 and threadedly engaged by respective nuts 200.Likewise, bolts 198 extend through aligned holes 128 and 150. Bolts 198also extend through aligned holes 122 and 178 as well as through alignedholes 124 and 180.

When assembled, flange 134 of connection member 130 and vertical segment80 of flange 42 are secured to one another by the respective bolts andnuts to form a vertical parallel pair of abutting flanges. Likewise,tongue 116 and the front portion of lower flange 164 of I-beam 158 aresecured by respective bolts and nuts to form a second pair of parallelabutting flanges which extend transversely to and most typicallyperpendicularly to flanges 134 and 80. Semicircular weld 196 extendswithin the right angle formed between these two pairs of parallelflanges with its lower quarter circle portion disposed directly betweenthe two pairs of flanges.

Thus, front connection 10 provides a substantially improved connectionbetween the front and rear sections 18 and 20 of the frame of drop decktrailer 12. The semicircular weld 196 helps to reduce cracking in theconnection by minimizing stress points found in linear welds. Inaddition, the L-shaped and S-shaped structures of flanges 42 and 44 helpprovide structural integrity to the connection. The heat treatment ofthe T-bars forming flanges 42 and 44 likewise provide additionalstrength and reduce or eliminate built in stresses which would otherwiseremain from the bending of these two bars. The L-shaped and S-shapedwelds along flanges 42 and 44 provide further structural integrity tothe connection. The use of tongue 116 which is formed integrally duringextrusion with the lower T-bar forming flange 44 provides additionalstrength to the connection between S-shaped flange 44 and I-beam 158.These and other aspects of front connection 10 provide a substantiallyimproved connection.

In the foregoing description, certain terms have been used for brevity,clearness, and understanding. No unnecessary limitations are to beimplied therefrom beyond the requirement of the prior art because suchterms are used for descriptive purposes and are intended to be broadlyconstrued.

Moreover, the description and illustration of the invention is anexample and the invention is not limited to the exact details shown ordescribed.

The invention claimed is:
 1. A drop deck trailer frame comprising: afront section having a first upper surface; a rear section having asecond upper surface lower than the first upper surface; an S-shapedflange on the front section; an I-beam of the rear section defining thesecond upper surface and comprising a vertical plate having a top and abottom, an upper flange secured to the top of the vertical plate andhaving a front end, and a lower flange secured to the bottom of thevertical plate and having a front end; a first upwardly extending flangewhich extends from adjacent the front end of the upper flange toadjacent the front end of the tower flange; a second upwardly extendingflange which extends from adjacent the front end of the upper flange toadjacent the front end of the lower flange; and wherein the secondupwardly extending flange extends upwardly beyond the upper flange.
 2. Adrop deck trailer frame comprising: a front section having a first uppersurface; a rear section having a second upper surface lower than thefirst upper surface; an S-shaped flange on the front section; an I-beamof the rear section defining the second upper surface and comprising avertical plate having a top and a bottom, an upper flange secured to thetop of the vertical plate and having a front end, and a lower flangesecured to the bottom of the vertical plate and having a front end; afirst upwardly extending flange which extends from adjacent the frontend of the upper flange to adjacent the front end of the tower flange; asecond upwardly extending flange which extends from adjacent the frontend of the upper flange to adjacent the front end of the lower flange;and wherein the lower flange of the I-beam is directly above a portionof the S-shaped flange.
 3. A drop deck trailer frame comprising: a frontsection having a first upper surface; a rear section having a secondupper surface lower than the first upper surface; an S-shaped flange onthe front section; an I-beam of the rear section defining the secondupper surface and comprising a vertical plate having a top and a bottom,an upper flange secured to the top of the vertical plate and having afront end, and a lower flange secured to the bottom of the verticalplate and having a front end; a first upwardly extending flange whichextends from adjacent the front end of the upper flange to adjacent thefront end of the tower flange; a second upwardly extending flange whichextends from adjacent the front end of the upper flange to adjacent thefront end of the lower flange; and further comprising a plurality ofbolts extending from the S-shaped flange to the lower flange of theI-beam.
 4. A drop deck trailer frame comprising: a front section havinga first upper surface; a rear section having a second upper surfacelower than the first upper surface; an S-shaped flange on the frontsection; an I-beam of the rear section defining the second upper surfaceand comprising a vertical plate having a top and a bottom, an upperflange secured to the top of the vertical plate and having a front end,and a lower flange secured to the bottom of the vertical plate andhaving a front end; a first upwardly extending flange which extends fromadjacent the front end of the upper flange to adjacent the front end ofthe tower flange; a second upwardly extending flange which extends fromadjacent the front end of the upper flange to adjacent the front end ofthe lower flange; and further comprising a connection member which isformed from a T-bar and includes a semicircular fiat web and the firstupwardly extending flange.
 5. The frame of claim 4 wherein thesemicircular web has a semicircular edge; and the vertical plate of theI-beam has a semicircular front edge which is secured to thesemicircular edge of the web along a semicircular weld.
 6. A drop decktrailer frame comprising: a front section having a first upper surface;a rear section having a second upper surface lower than the first uppersurface; an S-shaped flange on the front section; an I-beam of the rearsection defining the second upper surface and comprising a verticalplate having a top and a bottom, an upper flange secured to the top ofthe vertical plate and having a front end, and a lower flange secured tothe bottom of the vertical plate and having a front end; a firstupwardly extending flange which extends from adjacent the front end ofthe upper flange to adjacent the front end of the tower flange; a secondupwardly extending flange which extends from adjacent the front end ofthe upper flange to adjacent the front end of the lower flange; andwherein the I-beam comprises an inverted T-bar which includes the lowerflange and a lower portion of the vertical plate; the I-beam comprises aT-bar which includes the upper flange and an upper portion of thevertical plate; and the lower and upper portions of the vertical plateare connected to one another along a substantially horizontal elongatedweld.
 7. The frame of claim 6 wherein the substantially horizontalelongated weld has a front end; and further comprising a semicircularweld which extends adjacent the front end of the substantiallyhorizontal elongated weld.
 8. The frame of claim 7 wherein thesemicircular weld intersects the substantially horizontal elongated weldat the front end of the substantially horizontal elongated weld.
 9. Adrop deck trailer frame comprising: a front section having a first uppersurface; a rear section having a second upper surface lower than thefirst upper surface; an S-shaped flange on the front section; an I-beamof the rear section defining the second upper surface and comprising avertical plate having a top and a bottom, an upper flange secured to thetop of the vertical plate and having a front end, and a lower flangesecured to the bottom of the vertical plate and having a front end; afirst upwardly extending flange which extends from adjacent the frontend of the upper flange to adjacent the front end of the tower flange; asecond upwardly extending flange which extends from adjacent the frontend of the upper flange to adjacent the front end of the lower flange;and further comprising a connection between the front and rear sections;and a semicircular weld on the connection.
 10. The frame of claim 9wherein the semicircular weld extends rearwardly from adjacent the frontend of the upper flange and extends rearwardly from adjacent the frontend of the lower flange.
 11. A drop deck trailer frame comprising: afront section having a first upper surface; a rear section having asecond upper surface lower than the first upper surface; an S-shapedflange on the front section; an I-beam of the rear section defining thesecond upper surface and comprising a vertical plate having a top and abottom, an upper flange secured to the top of the vertical plate andhaving a front end, and a lower flange secured to the bottom of thevertical plate and having a front end; an upwardly extending flangewhich extends from adjacent the front end of the upper flange toadjacent the front end of the lower flange; and an L-shaped flangeadjacent the upwardly extending flange; and wherein the L-shaped flangeextends upwardly beyond the upper flange of the I-beam.
 12. The frame ofclaim 11 wherein the L-shaped flange defines the first upper surface.13. The frame of claim 11 wherein the L-shaped flange has a generallyhorizontal leg which is higher than the upper flange of the I-beam. 14.A drop deck trailer frame comprising: a front section having a firstupper surface; a rear section having a second upper surface lower thanthe first upper surface; an S-shaped flange on the front section; anI-beam of the rear section defining the second upper surface andcomprising a vertical plate having a top and a bottom, an upper flangesecured to the top of the vertical plate and having a front end, and alower flange secured to the bottom of the vertical plate and having afront end; an upwardly extending flange which extends from adjacent thefront end of the upper flange to adjacent the front end of the lowerflange; and an L-shaped flange adjacent the upwardly extending flange;and further comprising an L-shaped plate; and a weld between theL-shaped plate and the L-shaped flange which secures the L-shaped plateto the L-shaped flange.
 15. The frame of claim 11 further comprising aplurality of bolts extending from the L-shaped flange to the upwardlyextending flange.
 16. A drop deck trailer frame comprising: a frontsection having a first upper surface; a rear section having a secondupper surface lower than the first upper surface; an S-shaped flange onthe front section; an I-beam of the rear section defining the secondupper surface and comprising a vertical plate having a top and a bottom,an upper flange secured to the top of the vertical plate and having afront end, and a lower flange secured to the bottom of the verticalplate and having a front end; an upwardly extending flange which extendsfrom adjacent the front end of the upper flange to adjacent the frontend of the lower flange; and an L-shaped flange adjacent the upwardlyextending flange; and further comprising a connection between the frontand rear sections; and a semicircular weld on the connection.
 17. A dropdeck trailer frame comprising: a front section having a first uppersurface; a rear section having a second upper surface lower than thefirst upper surface; a longitudinally extending I-beam of the rearsection defining the second upper surface and comprising a verticalplate having a top and a bottom, an upper flange secured to the top ofthe vertical plate and having a front end, and a lower flange secured tothe bottom of the vertical plate and having a front end; a firstupwardly extending flange of the rear section which extends fromadjacent the front end of the upper flange to adjacent the front end ofthe lower flange and which has a lower end; a second upwardly extendingflange of the front section which extends from adjacent the front end ofthe upper flange to adjacent the front end of the lower flange, whichextends upwardly beyond the upper flange and which has a lower end; alongitudinally extending third flange of the front section which extendsbelow the lower ends of the first and second upwardly extending flangesand includes a generally horizontal tongue which extends rearwardlybeyond the lower ends of the first and second upwardly extending flangesand below the lower flange; a plurality of first bolts extending fromthe first upwardly extending flange to the second upwardly extendingflange; and a plurality of second bolts extending from the tongue to thelower flange of the I-beam.
 18. The frame of claim 17 further comprisinga connection between the front and rear sections; and a semicircularweld on the connection.